class_docstr: Represents an algebraic operation, such as '+', '-', etc.
code: def __str__(self):
      return self.symbol
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from collections import namedtuple
  import random
  import six
  from six.moves import range
  import sympy
label_desc: Use image node_id 2 for calling the ExprOp obj's underlying member method code with example usage: obj.__str__() and returns: self